1. Field of the Invention
The present invention relates to an electronic paper display, especially to a border structure for viewable area of an electronic paper display, capable of reducing the chance of mura defects (uneven defects or inconsistent defects) occurring in the electronic paper display.
2. Description of the Related Art
As the pixels around the border of the viewable area of an electronic paper display are prone to be covered by an edge frame, four long rectangular edge regions of the viewable area are usually preserved as border regions with four corresponding long rectangular border electrodes equipped underneath. When in operation, the electronic paper display will apply a voltage to the border electrodes to determine the display color in the border regions. The display color in the border regions is usually set to be close to the color—black for example—of the edge frame of the electronic paper display, so that the border regions can act as buffer regions to absorb the width variations of the edge frame. Please refer to FIG. 1, which illustrates a rear view of a partial structure of a prior art electronic paper display. As illustrated in FIG. 1, the partial structure includes, from front to rear, a protection sheet 100, an FPL (Front Plane Laminate) 110, and an electrodes plane—including a border electrode 120 (corresponding to a border region) and a plurality of pixel electrodes 130.
In the structure, the protection sheet 100 is made of a transparent material. The FPL 110 includes a glue layer, an electrophoretic display layer, an ITO (Indium Tin Oxide) layer, and a PET (PolyEthylene Terephthalate) layer. The border electrode 120 and the pixel electrodes 130 are made of metal. When in operation, the electronic paper display will apply corresponding voltages to the pixel electrodes 130 and the border electrode 120 to generate electric fields for effecting the electrophoretic display layer, so that the FPL 110 will show a framed image.
As for the structure of the border regions, please refer to FIG. 2, which illustrates a partial sectional view of a border region. As illustrated in FIG. 2, the composition thereof includes, from top to bottom, a protection sheet 100, a FPL 110, a border electrode 120, and a planarization layer 140, wherein the FPL 110 includes, from top to bottom, a glue layer 111, an electrophoretic display layer 112, an ITO layer 113, and a PET layer 114. When a voltage difference is applied between the border electrode 120 and the ITO layer 113, an electrical field will be generated accordingly to effect micro capsules or micro cups of the electrophoretic display layer 112 in the border region, so as to make the FPL 110 display an edge band pattern.
However, when peel-offs occur in the interface between the glue layer 111 and the border electrode 120 under an environment of high temperature and high humidity, the electrical field distribution over the electrophoretic display layer 112 will become non-uniform, causing mura defects (uneven defects or inconsistent defects) to occur in the display of the edge band pattern.
To tackle the mentioned mura problem of the electronic paper display, the present invention proposes a novel border structure for viewable area of electronic paper display, which can enhance the adhesive effect of the glue layer, and thereby reduce the chance of mura defects occurring in the border regions of viewable area.